Linear Motor for Vacuum and Vacuum Processing Apparatus

ABSTRACT

A vacuum processing apparatus includes a linear motor. The linear motor includes a mover having a permanent magnet, a stator having a coil covered by a resin member, and a wire for supplying a current to the coil provided in a vacuum sample chamber. The wire is led out to an outside of the vacuum sample chamber through a through hole portion provided in the wall surface of the vacuum sample chamber. The through hole portion is filled with the resin member integrally or with a filler that binds to the resin member, so that the through hole portion is sealed.

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.16/600,010 filed Oct. 11, 2019, which claims priority from JapanesePatent Application No. 2018-196327, filed Oct. 18, 2018, the disclosuresof which are expressly incorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a linear motor for driving a samplestage in a vacuum sample chamber.

BACKGROUND ART

In a vacuum processing apparatus, represented by an electron microscope,an ion beam apparatus, a semiconductor manufacturing apparatus, and asemiconductor measurement and inspection apparatus, in which a sample isobserved, inspected, measured, analyzed, processed and conveyed(hereinafter referred to as “processing”) in a vacuum space, it isnormal to perform various processing on a target sample while moving thesample to be processed by a movable stage. A linear motor is employed asa driving mechanism for realizing high speed movement and high precisionpositioning of the movable stage used in the vacuum processingapparatus. The linear motor includes a moving magnet type linear motor.The moving magnet type linear motor includes a mover having a permanentmagnet and a stator having a coil through which a control currentpassing, and there is no need for power supply wires to movableportions, so that it suitable for a case where it is desired to reduce arisk of disconnection and foreign matter generation caused by movementof the power supply wires.

PRIOR ART LITERATURE Patent Literature

-   PTL 1: JP-A-2014-128177

SUMMARY OF INVENTION Technical Problem

Meanwhile, the moving magnet type linear motor using the coil as thestator requires a coil whose length corresponds to a movable stroke of astage. That is, if the stroke is intended to be long, the number of thecoils needs to be increased accordingly, and therefore the number ofwires to be introduced into a vacuum chamber in an electron microscopetends to increase. The increase in the number of the wires in the vacuumsample chamber leads to problems such as an increase in the number ofassembly operations, an increase in cost, and an increase in an amountof outgassing generated from wire coating. In order to solve theseproblems, PTL 1 discloses a linear motor in which an entire coil on astator side is covered by a packaging member having a vacuum sealingstructure, and a space between a mover having a permanent magnet and astator having a coil is airtightly separated.

However, in the technology disclosed in PTL 1, since the stator havingthe coil is disposed in an atmospheric environment, and the mover havingthe permanent magnet is disposed in a vacuum environment, the packagingmember is required to separate the space between the coil and thepermanent magnet, and a gap greater than or equal to a thickness of thepackaging member is generated between the coil and the permanent magnet.For example, in the vacuum sample chamber of the electron microscope, ahigh vacuum of 10-5 Pa may be required, and in order to secure amechanical strength of the packaging member for separating the vacuumenvironment and the atmospheric environment, a stainless packagingmember requires to a thickness of several centimeters. In the linearmotor, thrust efficiency decreases as the gap between the coil and thepermanent magnet increases, and therefore, when a distance between thestator and the mover is more than several centimeters, there is aproblem that thrust generation efficiency of the linear motor issignificantly reduced.

The invention is made in view of the above problems, and an objectthereof is to provide a linear motor capable of improving the thrustgeneration efficiency while reducing the amount of the outgassinggenerated from wire coating and the number of assembly operations of thelinear motor.

Solution to Problem

In order to the above problems, a linear motor for vacuum is provided,the linear motor for vacuum including: a mover having a permanentmagnet; and a stator having a support member to which a coil is fixed,in which the support member includes a vacuum sealing portion thatvacuum seals with a wall surface of a vacuum sample chamber, and afeed-through for supplying a current to the coil provided in the vacuumsample chamber.

A linear motor for vacuum is further provided, the linear motor forvacuum including: a mover having a permanent magnet; and a stator havinga coil covered by a resin member, in which the stator includes a supportmember having a vacuum sealing portion that vacuum seals with a wallsurface of a vacuum sample chamber and a first through hole portion, anda wire for supplying a current to the coil provided in the vacuum samplechamber. The wire is led out to an outside of the vacuum sample chamberthrough the first through hole portion. The first through hole portionis filled with the resin member integrally or with a filler that bindsto the resin member, so that the through hole portion is sealed.

Further, a vacuum processing apparatus including a linear motor forvacuum is provided. The linear motor for vacuum includes a mover havinga permanent magnet, a stator having a coil covered by a resin member,and a wire for supplying a current to the coil provided in a vacuumsample chamber. The wire is led out to an outside of the vacuum samplechamber through a through hole portion provided in the wall surface ofthe vacuum sample chamber. The through hole portion is filled with theresin member integrally or with a filler that binds to the resin member,that the through hole portion is sealed.

Advantageous Effect

According to the above configuration, it is possible to implement alinear motor capable of preventing outgassing generated from wirecoating in a vacuum sample chamber, and having excellent assemblyoperation efficiency and maintainability and high thrust generationefficiency, and a vacuum processing apparatus using the linear motor.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a view illustrating a sample stage which uses a linear motorof a first embodiment as a drive source.

FIG. 2 is a cross-sectional view of the stage of FIG. 1 taken along aline A-A.

FIG. 3 is a view illustrating the configuration of a peripheral portionof a stator according to the first embodiment.

FIG. 4 is a view illustrating the configuration of a peripheral portionof a stator according to a second embodiment.

FIG. 5 is a view illustrating the configuration of a peripheral portionof a stator according to a third embodiment.

FIG. 6 is a view illustrating the configuration of a peripheral portionof a stator according to a forth embodiment.

FIG. 7 is a view illustrating the configuration of a peripheral portionof a stator according to a fifth embodiment.

FIG. 8 is a view illustrating the configuration of a peripheral portionof a stator according to an embodiment of the invention.

DESCRIPTION OF EMBODIMENTS

Hereinafter, embodiments will be described with reference toaccompanying drawings. In the accompanying drawings, elements with thesame functions may be denoted by the same number. Although the attacheddrawings show specific embodiments in accordance with the principles ofthe disclosure, they are for the purpose of understanding thedisclosure, and are not to be used for limiting interpretation of thedisclosure. The descriptions in this specification are merely exemplary,and are not intended to limit the scope of the claims or application inany way whatsoever.

This embodiment has been described in sufficient detail for thoseskilled in the art to practice the present disclosure, but otherimplementations are possible and do not depart from the scope and spiritof the technical idea of the present disclosure. It is necessary tounderstand that it is possible to change the composition/structure andreplace various elements. Therefore, the following description shouldnot be interpreted as being limited to this.

In the following embodiments, a linear motor used for a sample stage in,for example, an electron microscope will be described as an example, theinvention is not limited thereto, and can be applied to a vacuumprocessing apparatus, represented by an electron microscope, an ion beamapparatus, a semiconductor manufacturing apparatus, and a semiconductormeasurement and inspection apparatus in which a sample is observed,inspected, measured, analyzed, processed, and conveyed in a vacuumspace.

First Embodiment

Hereinafter, an embodiment of the invention will be described withreference to FIGS. 1 to 3.

FIG. 1 illustrates a configuration example of a sample stage driven by alinear motor in a vacuum sample chamber of an electron microscope or thelike. A space of a vacuum sample chamber inside 19 and an atmosphericenvironment 20 are separated by a vacuum sample chamber wall 10. Asample stage 2 includes an X movable table 5, a Y movable table 6, an Xroller guide 8 and a Y roller guide 9 for moving each table linearly inrespective axial directions, and a chuck 7 for fixing a sample. A stator3 and the vacuum sample chamber wall 10 are mechanically fixed by screwsor the like. The X movable table 5 and a mover 4 are mechanically fixedby screws or the like, and thrust of a linear motor 1 is transmitted tothe X movable table 5. The linear motor 1 includes a stator 3 having acoil and a mover 4 having a magnet, and is disposed at the vacuum samplechamber inside 19.

FIG. 2 is a cross-sectional view of the sample stage of FIG. 1, and across-sectional position and a direction are taken along a line A-A inFIG. 1. In this embodiment, the stator 3 is a common design, and aplurality of the stators 3 are combined according to a desired stroke ofthe sample stage 2, and the embodiment of FIG. 2 illustrate an examplein which four common design stators 3 a, 3 b, 3 c, and 3 d are arrangedin the X direction. In this way, the stator can be commonly designed anda plurality of stators are used in combination according to the stroke,so that it is not necessary to prepare a stator having a new length foreach sample stage with a different stroke, and a cost reduction effectcan be expected when a sample stage of multiple types is desired to bemanufactured. Meanwhile, since a stroke of the sample stage 2 isdetermined by the number of the stators 3, when the stroke is increased,the number of the wires 12 connected to the stator 3 also increases withthe increase of the number of the stators 3. In FIG. 2, since fourstators 3 a, 3 b, 3 c, and 3 d are arranged in the X direction of thesample stage 2, four wires 12 a, 12 b, 12 c, and 12 d are required forrespective stators. If the number of the wires increases in the vacuumsample chamber inside 19, it would cause problems of an increase ofoutgassing from wire coating and an increase in the number of assemblyoperations. An embodiment of the invention for solving the problems willbe described with reference to FIG. 3.

FIG. 3 illustrates an example of a peripheral portion of the statoraccording to the embodiment of the invention. The stator 3 includes acoil 11, a supporting member 13, wires 12 for connecting to the coil 11,and a vacuum feed-through 21 for taking the wires 12 out of the vacuumsample chamber inside 19 to the atmospheric environment. The vacuumfeed-through 21 that separates the vacuum sample chamber inside 19 andthe atmospheric environment 20 from each other may be made of resin. Thesupport member 13 and the coil 11 are fixed to each other by an adhesiveor the like. The support member 13 is made of metal or resin. Epoxyresin is an example of the resin that can be used for forming the vacuumfeed-through 21 and fixing the coil 11. Since the epoxy resin isavailable in adhesive type and can be cured to a desired shape aftercovering the corresponding portion, it also can be easy to form thevacuum feed-through 21 and to fix the support member 13 and the coil 11.

In the support member 13 of the stator 3, a hole for fixing the screw bywhich the stator 3 is attached to the vacuum sample chamber wall 10 isformed (not shown). The stator 3 is configured to be screwed to thevacuum sample chamber wall 10, so that it is possible to singly attachand detach the stator 3, and to easily perform component replacement.The support member 13 of the stator 3 is provided with a vacuum sealingstructure. An example of the vacuum sealing structure is a sealingstructure with an O-ring. In the embodiment of FIG. 3, an O-ring groove16 for attaching an O-ring 15 to the support member 13 is provided, anda sealing surface is formed on an O-ring contact surface of the O-ringgroove 16 by machining or the like, and a sealing surface is also formedon a surface of the vacuum sample chamber wall 10 that is also incontact with the O-ring 15. A through hole 14 for taking the wires 12 toa side of the atmospheric environment 20 is formed in the vacuum samplechamber wall 10.

According to the above configuration, in the related art, the wires 12to the stator 3 that is routed in the vacuum sample chamber can bedirectly taken out to the atmospheric environment, so that theoutgassing generated from the wire coating in the vacuum sample chambercan be prevented. Further, since the wire to the linear motor does notrequire to be taken into the vacuum sample chamber, efficiency ofassembly operations is improved. Further, the stator having the coil 3and the mover having the permanent magnet are not required to beseparated spatially, and are both disposed in the vacuum sample chamber,so that a linear motor with a small gap between the coil and thepermanent magnet can be realized, and thrust generation efficiency ofthe linear motor can be improved. Further, single component replacementcan be performed on the stator 3, so that workability such asmaintenance is excellent.

Further, as will be described later in a fourth embodiment, the vacuumfeed-through 21 may be configured to supply a cooling fluid for coolingthe coil. In this case, the same effects as those described in thefourth embodiment can be obtained.

Second Embodiment

FIG. 4 illustrates the configuration of a peripheral portion of a statoraccording to another embodiment of the invention. A stator 3 includes acoil 11, wires 12 for connecting to the coil 11, and resin 17. The resin17 is configured to be a member that covers the coil 11, the wires 12and a through hole 14, and separates a vacuum sample chamber inside 19and an atmospheric environment 20 from each other. In other words, thethrough hole 14 is sealed by the resin 17, so that the airtightnessbetween the vacuum sample chamber inside 19 and the atmosphericenvironment 20 is ensured. In addition, the coil 11 is covered with theresin 17 to ensure rigidity and to prevent a shape change of the coil11, so that the performance of a linear motor can be stabilized over along period. In this case, in order to support the coil 11, not only theresin 17 but also a new support member may be added. The shape of theresin 17 can be formed by a molding method such as injection molding orinsert molding.

In this embodiment, compared with the first embodiment, although thesingly component replacement cannot be performed, the cost of the linearmotor can be reduced since the number of components on a side of thestator having the coil 11 can be reduced.

Third Embodiment

FIG. 5 illustrates the configuration of a peripheral portion of a statorin another embodiment of the invention. A stator 3 includes a coil 11,wires 12 for connecting to the coil 11, resin 17, and a support member22. The resin 17 is configured to be a member that covers the coil 11,the wires 12 and a through hole 14 of the support member 22, andseparates a vacuum sample chamber inside 19 and an atmosphericenvironment 20 form each other. That is, the through hole 14 is sealedby the resin 17, so that the airtightness between the vacuum samplechamber inside 19 and the atmospheric environment 20 is ensured. Inaddition, the coil 11 is covered with the resin 17 to ensure rigidityand to prevent a shape change of the coil 11, so that the performance ofa linear motor can be stabilized over a long period. In the supportmember 22, a hole for fixing a screw by which the stator 3 is attachedto a vacuum sample chamber wall 10 is formed (not shown), such thatattachment and detachment of the stator 3 can be singly performed.Further, the support member 22 is provided with an O-ring groove 16 towhich an O-ring 15 is attached, and a sealing surface is formed on anO-ring contact surface of the O-ring groove 16 by machining or the like.Similarly, a sealing surface is also formed on a surface of the vacuumsample chamber wall 10 that is also in contact with the O-ring 15. Avacuum sealing structure with the O-ring 15 maintains the airtightnessbetween the support member 22 and the vacuum sample chamber wall 10.

In the present embodiment, the same effect as the first embodiment canbe acquired.

Fourth Embodiment

FIG. 6 illustrates the configuration of a peripheral portion of a statorin another embodiment of the invention. The third embodiment is aconfiguration example in which a pipe 18 is further added for supplyinga cooling fluid for cooling a coil 3. When heat of the coil istransmitted to a sample chamber or a movable table, an orientationchange of the movable table or deformation of the movable table occurs.Such orientation change or deformation of the movable table causes achange in a stage coordinate measurement position or an electron beamirradiation position in the vacuum processing apparatus, which may causedeterioration in processing performance of the vacuum processingapparatus. Therefore, it can be said that suppressing heat generation ofthe coil generated during stage operations is a serious problem forachieving both acceleration of the stage (large current of the coil) andhigh accuracy of the stage. As an example of a cooling method of thevacuum sample chamber and the stage, as shown in FIG. 8, there is amethod of disposing the pipe 18 for cooling fluid on a bottom surface 25of an atmospheric side of the sample chamber. If the pipe 18 is coveredwith a metal jacket 24 so as to bring the pipe 18 in close contact withthe sample chamber bottom surface 25, the pipe 18 can be mechanicallyfixed to the sample chamber bottom surface 25 by using screws or thelike. However, in the configuration of FIG. 8, the heat, as shown in aheat flow 26, generated in the coil 11 is transmitted to the pipe 18 forcooling fluid via the sample chamber bottom surface 25, and thus, theheat is inevitably transmitted to the vacuum sample chamber or themovable table. Compared with the configuration of FIG. 8, in thisembodiment of FIG. 6, since the pipe 18 for cooling fluid can bedisposed closer the coil 11 which is a heat source, the heat generatedin the coil 11 can be more directly released to the cooling fluid, andthe heat transmission to the vacuum sample chamber can be suppressed.For example, water or an aqueous solution to which a specific substanceis added is used as the cooling fluid. The stator 3 includes the coil11, wires 12 for connecting to the coil 11, resin 17, a support member21 and the pipe 18. A method in which the support member 22 is made of acast-metal object is an example of a manufacturing method of the presentembodiment shown in FIG. 6. If the pipe 18 for cooling that is processedto a size that fits in the support member 22 in advance is disposed inthe cast-metal object, and a metal material used as the support member22 is melted and poured and cured, the pipe 18 for cooling can be easilydisposed inside the support member 22. Aluminum or the like which hasgood thermal conductivity and can be easily manufactured by a castingmethod is an example of the metal material. The resin 17 is configuredto be a member that covers the coil 11, the wires 12, the pipe 18 andthe through hole 23 of the support member 22, and separates a vacuumsample chamber inside 19 and an atmospheric environment 20 form eachother. That is, by sealing the through hole 23 with the resin 17, theairtightness between the vacuum sample chamber inside 19 and theatmospheric environment 20 is ensured.

In the present embodiment, heat generation of the coil 11 can beefficiently suppressed by cooling effect of the cooling fluid, and heattransmitted to the vacuum sample chamber and the movable table can besuppressed, so that deterioration in the processing performance of thevacuum processing apparatus can be prevented. In addition, the presentembodiment is also suitable for a linear motor driving with a largecurrent. In addition, the pipe 18 for supplying the cooling fluid forcooling the coil 11 needs to be disposed in the vacuum sample chamberinside 19, the pipe 18 for cooling water of the present embodiment canbe airtightly separated from the vacuum sample chamber inside 19 withthe resin 17, so that no water leaks into the vacuum sample chamberinside 19 even when there is water leakage from the pipe 18 for watercooling.

Fifth Embodiment

FIG. 7 illustrates the configuration of a peripheral portion of a statorin another embodiment of the invention. With respect to the thirdembodiment, a position of an O-ring groove 16 provided in a supportmember 22 is changed, and a stator 3 is attached to a vacuum samplechamber wall 10 from a side of an atmospheric environment 20 in thepresent embodiment. A sealing surface is formed by machining or the likeon an O-ring contact surface of the O-ring groove 16 and an O-ringcontact surface of the vacuum sample chamber wall 10.

In the present embodiment, not only singly component replacement can beperformed on the stator 3, but also the stator 3 can be attached ordetached from the side of the atmospheric environment 20, workabilitysuch as maintenance is more excellent.

REFERENCE SIGN LIST

-   1 Linear motor-   2 Sample stage-   3 Stator-   4 Mover-   5 X movable table-   6 Y movable table-   7 Chunk-   8 X roller guide-   9 Y roller guide-   10 Vacuum sample chamber wall-   11 Coil-   12 Wire-   13 Support member-   14 Through hole-   15 O-ring-   16 O-ring groove-   17 Resin-   18 Pipe-   19 Vacuum sample chamber inside-   20 Atmospheric environment-   21 Vacuum feed-through-   22 Support member-   23 Through hole-   24 Jacket-   25 Bottom surface of sample chamber-   26 Heat flow

1. A vacuum processing apparatus comprising: a linear motor for vacuumthat includes a mover having a permanent magnet, a stator having a coilcovered by a resin member, and a wire for supplying a current to thecoil provided in a vacuum sample chamber, wherein the wire is led out toan outside of the vacuum sample chamber through a through hole portionprovided in the wall surface of the vacuum sample chamber, and thethrough hole portion is filled with the resin member integrally or witha filler that binds to the resin member, so that the through holeportion is sealed.
 2. The vacuum processing apparatus according to claim1, wherein a pipe configured to supply a fluid for cooling the coil isled out to the outside of the vacuum sample chamber through the throughhole portion.
 3. The vacuum processing apparatus according to claim 1,wherein the resin member covers the coil, the wire and the through holeportion, and is configured to separate the vacuum sample chamber andatmosphere environment.
 4. The vacuum processing apparatus according toclaim 1, wherein the resin member is formed by injection molding orinsert molding.
 5. The vacuum processing apparatus according to claim 1,further comprising a support member for supporting the coil.
 6. Thevacuum processing apparatus according to claim 2, wherein the resinmember covers the coil, the wire, the pipe, and the through holeportion, and is configured to separate the vacuum sample chamber andatmosphere environment.
 7. The vacuum processing apparatus according toclaim 1, wherein the resin member or the filler is epoxy resin.